Sortable Mixin

Description

Sortable mixin, most of the time used with a UL HTML tag. After each sort,
an ajax request will be send to the server, with as parameter a comma-separated
list containing the ids of the ordered li tag.
When you will use this mixin, you will be able to catch the JQueryEventConstants.SORTABLE
event in your Java Class. Your method will have on parameter : the comma-separated list of ids.